FIELD OF THE INVENTION
This invention relates to expandable endoprosthesis devices, generally referred to as stents, which are adapted to be implanted into a patient's body lumen, such as blood vessel or coronary artery, to maintain the patency thereof. These devices are useful in the treatment of atherosclerotic stenosis in blood vessels.
Stents are generally tubular-shaped devices which function to hold open a segment of a blood vessel or other anatomical lumen. They are particularly suitable for use to support and hold back a dissected arterial lining which can occlude the fluid passageway therethrough and to hold open a coronary artery after an angioplasty procedure.
Further details of prior art stents can be found in U.S. Pat. No. 3,868,956 (Alfidi et al.); U.S. Pat. No. 4,512,338 (Balko et al.); U.S. Pat. No. 4,553,545 (Maass et al.); U.S. Pat. No. 4,733,665 (Palmaz); U.S. Pat. No. 4,762,128 (Rosenbluth); U.S. Pat. No. 4,800,882 (Gianturco); U.S. Pat. No. 4,856,516 (Hillstead); and U.S. Pat. No. 4,886,062 (Wiktor), which are hereby incorporated herein in their entirety by reference thereto.
Various means have been described to deliver and implant stents. One method frequently described for delivering a stent to a desired intraluminal location includes mounting the expandable stent on an expandable member, such as a balloon, provided on the distal end of an intravascular catheter, advancing the catheter to the desired location within the patient's body lumen, inflating the balloon to expand the stent into a permanent expanded condition and then deflating the balloon and removing the catheter.
Prior art stent designs provide a stent that is composed of wire mesh or weave having an open lattice structure or patterns. The open lattice structure of the prior art stents generally provide uniform strength along the center of the stent, but may be weak at the ends. This configuration may cause the prior art stents to be weaker at the stent ends because each portion at the ends has only one neighboring support portion. This inherent weakness at the ends of the prior art stents could result in the ends decreasing in diameter after implantation in a body lumen.
It may therefore be important to improve existing stent designs to provide stronger ends while allowing the centers to maintain the radial rigidity needed to hold open a body lumen while at the same time maintaining the longitudinal flexibility of the stent to facilitate its delivery into the blood vessel. The present invention satisfies these needs.